Process of making cyanine dyes and certain products



United States Patent PROCESS OF MAKING CYANINE DYES AND CERTAIN PRODUCTSHenri Lariv, Clichy, and Pierre D. Collet, Vincennes,

France, assignors to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey No Drawing. Application September 26, 1952,Serial No. 311,784

Claims priority, application France June 18, 152

11 Claims. (Cl. 260-240.7)

S W C-SOHi 1150 CH3 I As can be readily seen from the above equation,this method has the grave disadvantage of yielding a gaseous mercaptan(CHsSl-I), which is highly poisonous. Moreover, any mercaptan remainingas an impurity is quite harmful to photographic emulsions.

Another known method for preparing cyanine (mono methine) dyes comprisesreacting a quaternary salt containing a reactive methyl group with aquaternary salt containing an iodo group in the 2-position. This methodyields only the dye iodides, which have limited solubility in alcohol,and in order to produce the dye chloride,

bromide, etc, which have greater alcohol solubility, it

is necessary to resort to further processing.

Instead of employing a cyclammonium quaternary salt containing areactive methyl group in the condensations with the mercapto or iodocompounds described above, it is possible to employ an intracyclicketomethylene compound and produce a merocyanine dye.

It is, accordingly, anobject of our invention to provide an improvedmethod for making cyanine (monomethine) and merocyanine dyes. Anotherobject is to .,,,provide a method for making cyanine (monomethine) andmerocyanine dyes without the attendant formation of poisonous mercaptangases or liquids. Still another object is to provide new intermediatesfor making cyanine (monomethine) and merocyanine dyes. Another object isto provide a method for making these new intermediates. Other objectswill become apparent from a con sideration of the following descriptionand examples.

According to our invention we prepare cyanine (monomethine) andmerocyanine dyes by condensing a cyclamice monium compound selected fromthose represented by the following general formulas:

as? o-so3R X and 11. ,21.

RI-ri is-S03 wherein R and R1 each represents an alkyl group, such asmethyl, ethyl, n-propyl, n-butyl, etc., X represents an anion, such asmethylsulfate, ethylsulfate, benzenesulf fonate, p-toluenesulfonate,Xylenesulfonate, iodide, bromide, etc., Z represents the non-metallicatoms necessary to complete a heterocyclic nucleus selected from thoseof the benzothiazole series or the naphthothiazole series, and Z1represents the non-metallic atoms necessary to complete a heterocyclicnucleus selected from those of the quinoline series or the pyridineseries, with a cyclammonium quaternary salt or an intracyclicketomethylene compound.

Advantageously, the condensations can be carried out in the presence ofa basic condensing agent, e. g. triethylamine, tri-n-propylamine,tri-n-butylamine, triisobutylamine, N-methylpiperidine,N-ethylpiperidine, N,N'-dimethylaniline, pyridine, etc. Inert solvents,e. g. carboxylic anhydrides (e. g. acetic anhydride, etc.), 1,4-dioxane, piperidiue, acetic acid, formamide, nitromethane, nitrobenzene,cresols, etc., can also be employed, if desired. Heat accelerates thecondensations, and temperatures varying from room temperature (ca. 20C.) to the reflux temperature of the reaction mixture can be used.

The cyclammonium quaternary salts which can be used in preparing thecyanine (monomethine) dyes of our vention by condensation with thecompounds of Formula I or II above can be advantageously represented bythe following general formula:

III.

wherein n represents a positive integer of from 1 to 2, R represents analkyl group (i. e. an alcohol radical), e. g. methyl, ethyl, n-propyl,isobutyl, n-butyl, n-amyl, isoamyl (e. g. an alkyl group of the formulaCmH2m+1 wherein m represents a positive integer of from 1 to 5),,3-hydroxyethyl, 'y-hydroxypropyl, fi-methoxyethyl, ,8- ethoxyethyl,allyl, S-methallyl, benzyl (phenylmethyl), 13- phenylethyl,B-carboxyethyl, carboxymethyl, a-carboxyethyl, 'y-carboxypropyl,,B-acetoxyethyl, -acetoxypropyl, carbomethoxymethyl,,G-carbomethoxyethyl, carbethoxymethyl, p-carbethoxyethyl,fi-sulfoethyl, phenylmercapto methvl, phenoxymethyl,li-phenylmercaptoethyl, ti-phenoxyethyl, etc., X1 represents an anion,e. g. chlo-' ride, bromide, iodide, thiocyanate, sulfamate,methylsulfate, ethylsulfate, perchlorate, benzenesulfonate,p-toluenesulfonate, xylenesulfonate, etc. and Z2 represents thenon-metallic atoms necessary to complete a heterocyclic nucleus selectedfrom the group consisting of those of the thiazole series (e. g.thiazole, 4- methylthiazole, S-methylthiazole, 4-phenylthiazole, '5-phenylthiazole, 4,5-dimethylthiazole, 4,5-dipheny1thiazole,4-(2-tl1ienyl)thiazole, etc.), those of the benzothiazole series (e. g.benzothiazole, 4-chlorobenzothiazole, 5- chlorobenzothiazole,6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole,S-methylbenzothiazole, 6-methylbenzothiazole, S-bromobenzothiazole,6-bromobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole,4-methoxybenzothiazole, S-methoxybenzothiazole, 6-rnethoxybenzothiazole, S-iodobenzothiazole, 6-iodobenzothiazole,4-ethoxybenzothiazole, S-ethoxybenzothiazole, tetrahydrobenzothiazole,5,6-dimethoxybenzothiazole, 5,6

dioxymethylenebenzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole, etc.), those of the naphthothiazcle series (e. g.a-naphthothiazole, fi-naphthothiazole, 5-- methoxyfi-naphthothiazolc,5-ethoxy-o-naphthothiazole, 7-methoXy-wnaphthothiazole,S-methOXy-a-naphmothia zole, etc), those of thethionaphtheno-7,6,4,5-thiazole series (e. g.4-methoxythionaphtheno-7,6,4,5-thiazole, etc.), those of the oxazoleseries (e. g. 4-methyloxazole, S-methyloxazole, 4-phenyloxazole,4,5-diphenyloxazoie, 4- ethyloxazole, 4,5-dimethyloxazolc,S-phenyloxazole, etc), those of the benzoxazole series (e. g. be rude,5- chlorobenzoxazole, S-phenylhenzoxazole, S-methyl'oenzoxazole,6-methyibenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole,S-methoxybenzoxazole, 6-methoxybenzoxazole, S-ethoxy'oenzoxazole,6-chlorobenzoxa zole, S-hydroxybenzoxazole, 6-hydroxybenz w those of thenaphthoxazole series (e. g. a-nsphthcxassle, ,B-naphthoxazole, etc),those of the selenazole series (e. g. 4-methylselenazole,4-phenylselenazole, etc), those of the benzoselenazole series (e. g.benzoselenazole, 5chlorobenzoselenazole, 5-methoxybenzoselenazole,S-hydroxybenzoselenazole, tetrahydrobenzoselenazoie, etc), those of thenaphthoselenazole series (e. g. a-naphthoselenazole,,B-naphthoselenazole, etc), those of the thiazoiine series (e. g.thiazoline, 4-methylthiazoline, etc), those of the dimethylpyridine,4,5-dimethylpyridine, 4,6-dimethylpyril dine, 4-chloropyridine,S-chloropyridine, 6chloropyridine, 3-hydroxypyridine, 4-hydroxypyridine,S-hydroxypyridine, 6-hydroxypyridine, 3-phenylpyridine,4-phenylpyridine, 6- phenylpyridine, etc.), those of the 4-pyridineseries (e. g. 2-methylpyridine, 3-rnethylpyridine, Z-chloropyridine, 3-chloropyridine, 2,3-dimethylpyridine, 2,5-dimethylpyridine,2,6-dimethylpyridine, Z-hydroxypyridine, S-hydroxypyridine, etc.), etc.In addition, R can represent an aryl group, e. g. phenyl,p-chlorophenyl, etc. when Z2 represents the non-metallic atoms necessaryto complete a heterocyclic nucleus of the thiazole, thiazoiine,benzothizu zole or 3,3-dialkylindolenine series. Those cyclammoniumquaternary salts represented by Formula ill wherein R represents aprimary alkyl group containing from i to 5 carbon atoms, e. g. methyl,ethyl, n-propyl, isobutyl, n-butyl, n-amyl, isoamyl, B-hydroxyethyl,-hydroxypropyl, ,B-methoxyethyl, B-ethoxyethyl, aliyl, fi-methailyl,B-carboxyethyl, carboxymethyl, fi-carbethoxyethyl, carbethoxymethyl,etc., are especially useful in practicing our invention.

The intracyclic ketomethylene compounds useful in practicing ourinvention can advantageously be represented by the following generalformula:

wherein Q represents the non-metallic atoms necessary to complete aheterocyclic nucleus containing from 5 to 6 atoms in the heterocyclicring, such as, for example, a. thiazolone nucleus, for xample, a2,4(3,5)-thiazoledione nucleus, such as 2,4(3,5)-thiazoledione,3-alkyl-2.4(3,5)- thiazolediones (e. g. 3-ethyl-2,4(3,5)-thiazoledione),3- phenyl-2,4(3,5)-thiazoledione, 3 u naphthyl 2,4(3,5)- thiazoledione,a 2-thio-2,4(3,5)-thiazoledione (a rhodanine) nucleus, such as a3-alkyl-2-thio-2,4(3,5)-thiazol- 4 dione (3-alkyl-rhodaninc) (e. g.3-ethyl-2-thio-2,4(3,5)- thiazoledione or B-ethyl-rhodanine,3-carboxymethyl-2- thio-2,4(3,5)-thiazoledione,3-carboxyethyl-2-thio-2,4-(3,- 5)-thiazoiedione,3sulfomethyl-2-thio-2,4(3,5)-thiazoledione, etc.),3-pl1enyl-2-thio-2,4(3,5)-thiazolcdione (3- phenylrhodanine), 3 pcarboxyphenyl-2-tl1io-2,4(3,5)- thiazoledione, 3 psulfophenyl-2-thio-2,4(3,5 )-thiazoledione, or 3-o-naphthyl-2-thio-2,4(3,5)-thiazoledione (3- u-naphthylrhodanine nucleior 3-(l-benzothiazyl)-2-thio- 2.4(3,5)-thiazcledionc (3 (lbenzothiazyl)rhodanine) nuclei, 2. Z-alkylmercapto-M5)thiazolonenucleus, such as 2-ethylmercapto-4(5)-thiazolone, a thiazolidonenucleus, such as 4-thiazolidone or its 3-alkyl (e. g. ethyl), 3-phenylor 3-a-naphthyl derivatives, a Z-alkylphenylaminolt5)- thiazolonenucleus or a 2-diphenylamino-4(5)-thiazol.one nucleus, an imidazolonenucleus, for example, a 2,4(3,5)- iinidazoledionc nucleus, such as2,4(3,5)-irnidazoledione (hydantoin) or its 3-alkyl (e. g. ethyl, etc.),3-phenyl or S-.-.-naphthyl derivatives as Well as its 1,3-dialkyl (c. g.1,3-diethy1, etc.), 1-alkyl-3-phenyl (e. g. l-cthyl-3-phenyi),l-alkyl-il-c-naphthyl (e. g. 1-ethyl-3-a-naphthyl), 1,3- diphenyl, etc.derivatives, a 2 thio-2,4(3,5)imiclazoledionc nucleus, such as2-thio-2,4(3,5)-irnidazoledione (2-thiohydantoin) or its 3-alkyl (e. g.methyl, ethyl, etc.), 3- phenyl or 3-naphthyl derivatives as well as itsl,3-dialkyl (e. g. 1,3-diethyl), 1-alkyl-3-phenyl (e. g.l-ethyl-3-phenyl, l-carboxymethyi-3-phenyl, 1-sulfomethyl-3-phenyl,etc), l-alkyl-3-naphthyl (e. g. l-ethyl-3-ct-naphthyl), 1,3- diphenyl,l-p-carboxyphenyl-3-phenyl, 1-p-sulfophenyl-3- phenyl, etc. derivatives;a pseudothiohydantoin nucleus (e. g. 2-iinino-4-thiazolidone, etc.);tetronic acid; countarones; homophthalimide; succinimide; an oxazolonenucleus, for example, a 2-thio-2,4(3,5)-oxazoledione nucleus, such as a3-allryl-2-thio-2,4(3,5)-oxazoledione nucleus (e. g.3-ethyl-2-thio-2,4(3,5)-oxazoledione) and a 2-imiuo-2,4(3,5 )-oxazolonc(a pseudohydantoin nucleus); 21 2-alkylmercapto-5(4)-imidazolonenucleus, such as 2- n-propylmercapto-5-(4)imidazolone; a thionaphthenonenucleus, such as 2(l)-thionaphthenone or l(2)-thionaphtlienone, apyrazolone nucleus (e. g. a 3-methyl-l-phenyl- 5-pyrazolone nucleus, al-p-carboxyphenyl-3-methyl-5- pyrazolone nucleus, a3-methyl-1-(4-sulfo-l-naphthyl)-5- pyrazoione nucleus, etc.); anoxindole nucleus, such as 2,3-dihydro-3-ketoindole, and likefive-membered heterocyclic nuclei; a 2,4,6-triketohexahydropyrimidinenucleus, for example, barbituric acid or Z-thiobarbituric acid as Wellas their l-alkyl (e. g. l-ethyl) or 1,3-dialkyl (e. g. 1,3-diethyl)derivatives; a 3,4-dihydro-2( l)-a uinolone nucleus, such as3,4-dihydro-2(1)-quinolone (dihydrocarbostyril); a3,4-dihydro-2(l)-quinoxalone nucleus, such as 3,4-dihydro-2(l)-quinoxalone (oxydihydroquinoxaline) 3 phenornorpholone (1,4,3benzoxazinc 3(4) one or hcnzo-fl-morpholone) nuclei;1,4,2-benzothiazine-3(4)- one (ketodihydrobenzoparathiazinc) nuclei, andthe like 3 siX-membered heterocyclic nuclei.

In addition to the cyclarnmonium quaternary salts represented by FormulaHI above, we have found that a new group of quaternary salts can beemployed to give trinuclear cyanine dyes. This new group of quaternarysalts can advantageously be represented by the following generalformula:

wherein R and X have the values given above and D represents thenon-metallic atoms necessary to complete a heterocyelic nucleus selectedfrom those of the benzothiazole series, those of the benzosolenazoleseries, or those of the naphthothiazole series, for example. Typicalcompounds embraced by Formula V above include, for example, 2 (2ethyl-3'-methylbenzothiazolyl)methyibenzothiazole methiodide,2-(2-ethyl-3'-methylbenzoelenazolyl)methylbenzoselenazole methiodid-e,2-(2- ethyl l' methyl p naphthothiazolyl)methyl 5' naphthothiazolemethiodide, etc.

The compounds represented by Formula I can be prepared by heating acompound selected from those represented by the following generalformula:

wherein Z has the values given above and M represents an alkali metalatom, together with an alkyl salt of the formula:

wherein R and X have the values given above. The compounds representedby Formula II can be prepared by heating a compound selected from thoserepresented by the following general formula:

IIa.

l\ CSO:-M wherein Z and M have the values given above, together with analkyl salt of the formula:

wherein Z and Z1 each have the values given above, in an aqueousalkaline solution of an oxidizing agent such as hydrogen peroxide orsodium hypochlorite. See, for example, U. S. 2,018,813; U. S. 2,108,712(Example 4); Br. 418,291; Br. 445,581; Fr. 772,968; Ger. 615,132; Ger.614,327; and Ital. 328,831. While the above oxidations have beenattempted with heterocyclic mercapto compounds other than thoserepresented by Formulas Ib and 11b, attempts to obtain quaternizedderivatives thereof were not successful, such as in the case of thebenzoxazole and thiazoline derivatives. This may have been due tounusually high solubility which prevented their separation in reasonablypure form, or their instability (as in the case of the tbiazolinederivative). The quaternary salts represented by Formulas I and 11 aboveare hywherein R and D have the values given above and a salt selectedfrom those represented by the following formula:

C. s 1 wherein X has the values given above.

Cir

e The following examples will serve to illustrate more fully the mannerwhereby we practice our invention.

Example 1.Methyl ester of the methyl sulfate of benzothiazole-Z-sulfonicacid N CH3 OSOzOCHa A mixture of 3.78 g. (0.02 mol.+50% excess) offreshly distilled dimethyl sulfate and 2.37 g. (0.01 mol.) of the sodiumsalt of benzothiazole-Z-sulfonic acid prepared, for example, in theknown manner, by oxidation of Z-mercaptobenzothiazole in an alkalinemedium, was heated at C. for 15-20 minutes. After cooling, the viscouspaste obtained was shaken with ether. A white product was obtained whichwas filtered, thoroughly washed with ether, dried and washedsuccessively with water and with acetone. 1.77 g. (yield 50%) of thedesired quaternary salt was obtained. Melting point, 290 C. Thequaternary salt was recrystallisable in acetic anhydride, but itpartially decomposed.

Analysis.S calculated: 27.06; S found: 26.9.

Example 2.-Methyl ester of the methyl sulfate ofa-naphthothizrzole-Z-sulfonic acid A mixture of 19 g. of dimethylsulfate (50% excess) and 14.4 g. of sodium a-naphthothiazolesulfonateprepared as described below was heated at C. for five minutes. The crudeproduct of the reaction was ground first with ether, then with a littleice-water, finally with acetone. 11.5 g. of the desired quaternary saltwas obtained, melting between IMO-345 C.

The sodium a-naphthothiazolesulfonate used in Example 2 was prepared asfollows: 71 g. of fi-naphthylamine, 76 g. of carbon disulfide and 32 g.of sulfur were heated in a bomb at 210 C. for 6 hours. The product wasextracted by two fractions of 1000 cc. of a normal solution of causticsoda, and acidified to Congo red by hydrochloric acid. The precipitatedmercaptan was washed with hot benzene and purified by dissolving incaustic soda and reprecipitating with acetic acid. 90 g. of mercaptanwas obtained. 2.17 g. (0.10 mol.) of the 2-mercapto-a-naphthothiazolethus prepared were dissolved in 500 cc. of a solution of 0.2N causticsoda. A little animal black was added and the mixture filtered. The

solution was cooled in ice and 83 cc. of 3.64 normal sodium hypochloritesolution added slowly while stirring vigorously, and the solution wasmaintained at 20 C. After completing the introduction of thehypochlorite the solution remained at the room temperature for 30minutes. 15.5 g. of the sulfonate was collected on a filter. By saltingout, a further 5 g. of the sodium salt was obtained.

Example 3.N-methylbezaine of quinoline-Z-sulfonic acid a sI or s 03 liaO CH;

20 cc. of dimethyl sulfate and 12.7 g. of sodium avoaeeu2-quinoline-sulfonate prepared as described below, were heated at 140150C. for 2.hours. After cooling, volumes of ether were added, then dried,and washed with ether. 18.2 g. of the crude product were obtained, mixedwith sodium methylsulfate; it was crystallised in alcohol. The desiredproduct decomposed before melting.

Analysis-N calculated: 6.28; found 6.40. lated: 4.04; found 4.26.

The sodium Z-quinoline sulfonate used in Example 3 was prepared in aknown manner (Ber. 53, 1017, 1920) by oxidation of Z-mercaptoquinolinewith concentrated nitric acid. 32 cc. of nitric acid (sp. gr. 1.37) werepoured carefully on 4 g. of 2-mereaptoquinoline. voluminous nitric acidfumes were given off and the product dissolved. A current of carbondioxide was passed through the solution until it was completely clear.The excess nitric acid was evaporated on a water bath. The residue wastreated with a saturated solution of sodium bicarbonate. The insolublematter was filtered and the sulfonic acid precipitated by dilutehydrochloric acid (1:1). 3.5 g. of the crude acid were obtained andpurified by dissolving in a bicarbonate solution and precipitating byhydrochloric acid. The product after purification melted at 370 C. Thesodium salt was prepared by heating the acid thus obtained on a waterbath with the calculated quantity of an ethyl alcohol solution of sodiumethylate, followed by evaporation to dryness. Yield 96%.

Example 4.N-methyl betaine of pyridine-Z-sulfonic acid cc. of dimethylsulfate and 7.95 g. of pyridine-2- sulfonic acid prepared as describedbelow were heated at H calcu- 150160 C. for five hours, cooled, 5volumes of ether added, dried, and washed with ether. 9.15 g. of thecrude product were obtained, recrystallisable in alcohol and melting at267268 C.

Analysis.N calculated: 8.1; found 8.3. lated: 4.05; found 4.11. Scalculated: 18.45.

Pyridine Z-sulfonic acid was prepared by oxidation of Z-mereaptopyridineby nitric acid. Into cc. of nitric acid (sp. gr. 1.37) to which wasadded 200 cc. of water,

H calcu- 20 g. of Z-mercaptopyridine were introduced in small portionswhile stirring. After the product dissolved, it was evaporated todryness on a water bath, and 20.5 g. of crude acid were obtained. Afterrecrystallisation in methanol, 11 g. of pure acid were collected,melting at 238 C.

Example 5.2-(2'-ethyl-3'-methylbcnz0th iazolyl) methylbeizzothiazolemethiodide El Calls 1 \i 18.45; found iii) as the starting material inExample 5.

Exrmzpirz 6.2-(2' ethyl 3 methylbenzoselenazolyl)-nieihylbenzoselenazole methiodide Example 7.2- (2 '-erhyl-1'-methyl-/3-naphthothiazolyl) methyl-fi-naphthothiazole methiodide Ccalculated /l I CH3 This quaternary salt was prepared in the same manneras that in Example 5 by replacing the methylene base used in thatexample by a molecularly equivalent amount of 3-met'nyl 2methylenefl-dihydronaphthothiazole (obtained from2-methyl-B-naphthothiazole metho-p-toluenesulfonate). It had meltingpoint 262 C. Yield Example 8.]'-erlzyl-3-methyIthiu-2-cyanine iodide3.55 g. (0.01 mol.) of themethyl ester of the methylsulfate ofbenzothiazole-2-sulfonic acid and 2.99 g. (0.01 mol.) of ethyl iodide ofquinaldine were introduced into a flask containing 75 cc. of ethylalcohol. 3 g. (0.02 mol. +50% excess) of anhydrous triethylamine wereadded. The mixture was heated for 20 minutes under reflux. The contentsof the flask were cooled in a refrigerating mixture, and the precipitatewas filtered and washed with water, then with acetone. fter drying, 4.2g. of the dye was obtained. Yield 94%. After crystallisation in 250 cc.of methyl alcohol, 3 g. of the dye represented by the above formula wasobtained.

Analysis.-S calculated: 7.37; found 7.34.

The same dye can be prepared using water as reaction medium. Forexample, a suspension of 7.1 g. of the quaternary salt obtained inExample 1 and 5.9 g. of the ethyl-p-toluenesulfonate of quinaldine weresuspended in cc. of ice Water. After cooling in ice, 6.25 cc. oftriethylainine were added while stirring as vigorously as possible. Thedye which separated from the beginning of the addition of thetriethylamine was collected on a. filter. It was dissolved in cc. ofboiling methanol and the solution was poured into 500 cc. of boilingwater containing 20 g. of potassium iodide. The dye precipitated 9immediately. The suspension was cooled, dried and washed with water, andthen with cold acetone. 4 g. of dye were obtained. Yield 45%.

Example 9.-3,3'dimethylthiacyanine iodide A mixture of 3.55 g. (0.01mol.) of the quaternary salt obtained according to Example 1, 2.75 g.(0.01 mol.) of the methyl sulfate of 2-methylbenzothiazole and 3 g.(0.02 mol. +50% excess) of triethylamine in 100 cc. of anhydrous ethylalcohol were heated under reflux. The crude product was poured into a100 ccl of hot water containing g. of potassium iodide. After cooling,the dye which separated was dried on a filter and then recrystallised in250 cc. of ethyl alcohol and filtered hot. After thoroughly cooling by arefrigerating mixture, the purified dye was separated and dried. 1.5 g.of the desired dye was obtained.

Example 10.3-ethyl-5- (3-methy l-2 (3 -benzothiaz0lylidene -2-thz'o-2,4(3,5 -0xaz0ledi0ne N (EH3 A mixture of 3.55 g. (0.01 mol.) of thequaternary salt obtained according to Example 1 and 1.45 g. (0.01 mol.)of 3-ethyl-2-thio-2,4(3,5)-oxazoledione in 50 cc. of anhydrous ethylalcohol was heated under reflux for minutes. The product was cooled by arefrigerating mixture and the precipitate collected on a filter. It waswashed with water and then by a little acetone. The crude dye weighed2.9 g. It was recrystallised from a mixture of equal parts of alcoholand pyridine. After drying, 2.5 g. of the desired dye was obtained,melting at 248 C. Yield 86.5%.

Analysis.S calculated: 21.93; found 22.0.

Example 11 -1 -carb0xymethyl-5 (3 -ethyl-2 3 -benz0- thiazolylidene)-3-phenyl-2-thi0hydant0in A mixture of 3.1 g. of the quaternary saltobtained in a manner similar to Example 1 (using ethyl sulfate insteadof methyl sulfate), 1.9 g. of 1-carboxymethyl-3- phenyl-Z-thiohydantoin,and 5211 cc. of triethylamine in 75 cc. of methyl alcohol was. heatedunder reflux for minutes, filtered hot, and the filtrate acidified withacetic acid. 500 cc. of water were added and the precipitate dried. 2.4g. of the crude dye were obtained (yield 79%), which was purified bydissolving in alcohol containing double the theoretical quantity of,triethylamine and reprecipitating with dilute hydrochloric acid.

Example 12.3-carb0xymethyl-5-(3-ethyl-2(3) benzothiazolylidene)rhodanineC2116 A mixture of 8 g. of the quaternary salt obtained in a mannersimilar to Example 1 (using ethyl sulfate instead of methyl sulfate),3.85 g. (0.02 mol.) of 3-carboxymethyl rhodanine and 100 cc. of methylalcohol to which had been added 9.5 g. of triethylamine was heated for10 minutes under reflux, filtered hot, and while still hot, acetic acidwas added to precipitate the dye. The product was cooled by arefrigerating mixture, the dye separated by filtration, washed with alittle methyl alcohol and dried. 6.3 g. of the crude dye (yield 89.5%)thus obtained were purified by dissolving the dye in the form of itstriethylamine salt in alcohol and acidification with acetic acid toliberate the acid.

The same dye can be prepared by using Water as a reaction medium. Atroom temperature and stirring vigorously, cc. of triethylamine wereadded to a suspension of 19.3 g. of 3-carboxymethyl rhodanine and 39.7g. of the quaternary salt obtained according to Example 1 in 300 cc. ofwater. After 15 minutes the mixture was warmed to C. and 500 cc. ofwater added to completely redissolve the triethylamine salt. Thesolution was filtered and the filtrate acidified with acetic acid.

Example I3.2-dipherzylamin0-5-(3-methyl-2 (3 -benz0- thiaz0lylia'ene)-4(5 -tl1ia z0l0ne I CH A mixture of 3.5 g. of the quaternary saltobtained according to Example 1 and 2.7 g. of Z-diphenylamino-4(5)-thiazolone, 50 cc. of methanol and 4.1 cc. of triethylamine washeated under reflux for 30 minutes, cooled and the product dried. 2.2 g.of the crude dye thus obtained were purified by dissolving in pyridineand reprecipitating with ethanol. The dye melted at 348 C.

Example 14.-3-methyl-4-(3-methyl-2 (3 -benzothiazolylidene-sulfophenyl-5-pyr0zalone A mixture of 4 g. of the ethylsulfate of ethylbenzthiazolyl sulfate, 2.55 g. of 3-methyl -1-sulfophenyl-5- pyrazolone,75 cc. of methyl alcohol and 7 cc. of triethylamine was heated underreflux for 30 minutes, filtered hot, ether added to the cooled filtrate,and the product dried. 3.9 g. of the crude dye thus obtained (yield 93%)were purified by dissolving in 40 cc. of hot methyl alcohol.

Example 15.3 ethyl-S- (3-methyl-2 (3)-benzothiazolylidene) rhodanine sO=CNCH L 2 5 c=c o=s S A mixture of 3.55 g. of the quaternary saltobtained according to Example 1, 1.6 g. of 3-ethylrhodanine and 4.1 cc.of triethylamine in 50 cc. of ethanol was heated under reflux, cooled,washed with water, then with acetone. The crude dye was purified bydissolving in the minimum quantity of pyridine and reprecipitating withmethanol. 2.9 g. of the desired dye were obtained.

Analysis-N calculated: 9.10; found 9.3.

Example 16.-1 '-ethyl-3-methyl-6,7-benzothia-2'-cyanine iodide A mixtureof 2 g. of the methyl ester of the methyl sulfate of wnaphthothiazole2-sulfonic acid, 1.5 g. of the ethyl iodide of quinaldine and 3 cc. oftriethylamine in 200 cc. of ethyl alcohol was heated under reflux for 15minutes. After cooling, filtration and drying 2.5 g. of the crude dyewere obtained. The dye can be recrystallised in methanol (700 cc. pergram).

AnaIysis.-N calculated: 5.65; found: 5.80. culated: 4.25; found: 4.27.

Example 17.-I',3 dimetizyi-4',5,6,7 dibenzothiacyaninep-toluenesulfonate A mixture of 2 g. of the quaternary salt obtainedaccording to Example 2, 1.9 g. of the methyl p-toluenesulfate of2-methy1-,8-naphthothiazole and 3 cc. of triethylamine in 200 cc. ofanhydrous ethyl alcohol was heated under reflux for 30 minutes. Aftercooling the solution, the dye of the above formula separated on afilter.

Erample 1 8 .3 -ethyl- 3 -methyl-Z-oc-naphthOthiazolylidene) -2-thi0-2,4(3,5 -0xaz0ledione F EA'tl/HIJIL J 9.-3 warboxymeth yl-5 3 -methyI-Z-a-naphth0t.-1iaz0lylidene) rhodanine A mixture of 2 g. of thequaternary salt obtained according to Example 2, 0.95 g. ofB-carboxymethylrhodanine and 5 cc. triethylamine in 120 cc. of ethanolwas heated under reflux for 15 minutes. After cooling, the raw dye wasdried and dissolved in alcohol. The alcohol solution was acidified withacetic acid, the dye recrystallised in acetic anhydride.

Amziysisu-S calculated: 24.6; found 24.8.

Example 20.3-ethyl-5-(Imethyl-2-quin0lylidene)- 2-thio-2,4- (3,5-0xaz0ledione A mixture of 0.36 g. of 3-ethy1-2-thi0-2,4(3,5)-oxazoledione, 1.5 g. of N-methyl-betaine of quinoline-Z-sulfonic acidand 0.85 cc. of triethylamine in cc. of ethanol was heated under refluxfor 20 minutes. 0.9 g. of the crude dye was obtained, and it wasrecrystallized in methanol.

Ana! :i. '.N calculated: 9.80; found: 9.65. culated: 4.90; found: 5.0.

H cal- Exnmple 21.--3-ethyl-5-(1-methyl-2-quin0lylidene)- rhodanine Amixture of 0.4 g. of 3-ethyl rhodanine, 0.87 g. of the N-methyl betaineof quinoline-2-sulfonic acid and 0.85 cc. of triethylamine in 10 cc. ofanhydrous ethanol was heated under reflux for 20 minutes. 0.95 g. of thecrude dye was obtained and it was recrystallized in 20 cc. of alcohol.

A. mlysis.S calculated: 21.19; found: 21.6.

Example 22.]ethyl-1-methyl-2,2-cyanine iodide Ha I A mixture of 1.49 g.of the ethyl iodide of quinaldine, 3.05 g. of the N-methyl betaine ofquinoline-Z-sulfonic acid and 1.5 cc. of triethylamine in 40 cc. ofethanol was heated under reflux for 20 minutes. 1.65 g. of crude dyewere obtained, which was recrystallized in 90 cc. of methanol.

Analysis.-N calculated: 6.36; found: 6.37. culated: 4.80; found: 4.97.

H cal- Example 23.1-ethyl-1-methyl-2-pyrizl0-2'-cyanine iodide I CH lCH3 I A mixture of 0.9 g. of the ethyl iodide of quinaldine, 0.9 g. ofthe N-methyl betaine of pyridine-Z-sulfonic acid and 0.85 cc. oftriethylamine in cc. of anhydrous ethanol was heated under reflux for 10minutes. 1.3 g. of the dye in a crude state were obtained, which wasrecrystallised in cc. of methanol.

Analysis.-N calculated: 7.18; found: 7.28. culated: 4.87; found: 4.87.

H cal- 13 Example 24.3-ethyl-J-(I-methyl-Z-pyridylidene)- 2-rhz'o-2,4(3,5 -oxazledione Example 25.3,3'-dimethyl-8-(2"-ethyl-3-methyl-2-benzothiazolinyl)-2,2-Zhiacyanine iodide /S l f;// a.

A mixture of 1.2 g. ,0.0025 mol). of the compound obtained according toExample 5, 0.9 g. (0.0025 mol.) of the quaternary salt obtainedaccording to Example 1 and 1 cc. of triethylamine (100% excess) in 20cc. of anhydrous ethyl alcohol was heated under reflux for 20 minutes,filtered hot, and the filtrate cooled with a refrigerating mixture ofice and alcohol. At the beginning of the precipitation, which was veryslow and which was brought about by rubbing the Walls of the receivingvessel with a stirrer, a quantity of anhydrous ether was added equal toa third of the volume of the solution. The crude dye after drying andWashing weighed 1 g. It was recrystallized in 20 cc. of methyl alcohol.This new compound gives a very intense red fluorescence in theultra-violet.

Analysis.N calculated: 6.89; found: 6.80.

Example 26.--3,3'-dimethyl-8-(2"-ethyl-3"-rizethyl- I2"-benzothiazolinyl) -6',7."-benz0thiacyanine iodide This dye can beprepared according to the process described in Example 25 by replacingthe quaternary salt obtained according to Example 1 by a molecularlyequivalent amount of the quaternary salt obtained according to Example 2(methyl ester of the methyl sulfate of a-naphthothiazole-iz-sulfonicacid)! 1 '14 Example 27.3,3'-dimethyl-8-(2"-ethyl-3"-methyl-2-benz0selenaz0linyl) -2,2'-thiaselenacyanine iodide This dye can beprepared according to the process described in Example 25 by replacingthe quaternary salt obtained according to Example 5 by a molecularlyequivalent amount of the quaternary salt obtained according to Example6.

Example 28.-3,3-dimethyl-8-(2-ethyl-3"-methyl-2- B-naphthothiazolinyl)-4,5-benz0-2,2'-thiacyanine iodide This dye can be prepared according tothe process described in Example 25 by replacing the quaternary saltobtained according to Example 5 by a molecularly equivalent amount ofthe quartenary salt obtained according to Example 7.

The dyes obtainable utilizing the intermediates represented by Formula Vabove and the new sulfonic esters or betaines of our inventionrepresented by Formulas I and II above can be represented by thefollowing general formula:

wherein R, R2, D1, and X have the values given above and Z is thecomposite symbol of Z and Z1 (i. e. represents the non-metallic atomsnecessary to complete a heterocyclic nucleus of the benzothiazole,naphthothiazole, pyridine or quinoline series). The new dyes representedby Formula D above can be used to alter the spectral sensitivity ofphotographic silver halide emulsions. Many of the dyes canadvantageously be used as ultra-violet filters in photographic elements.

The intermediates represented by Formula Ia above can also be preparedby intermixing a 2-halogeno cyclammonium base, e. g.2-chlorobenzothiazole, with an alkali metal sulfite, e. g. sodium orpotassium sulfite, in the form of an aqueous solution thereof.

In oxidizing the intermediates of Formulas Ib and IIb with hydrogenperoxide or sodium hypochlorite in an alkaline medium, We have foundthat it is advantageous to intermix the mercaptan and oxidizing agent atlow temperatures, e. g. 20-30 C. The yields are thereby increased andformation of the undesired Z-hydroxyl derivatives through decompositionis avoided. The oxidation can be completed by heating at about 80 C.after addition of the oxidizing agent has been completed and exothermicheat of reaction has been removed. The yield can be determined bydecomposing the 2-sulfonic acid salt with sulfuric acid in the presenceof iodine and back-titrating the excess iodine with sodium thiosulfate.

The intermediates represented by Formula I can be converted to 2-ketoderivatives by refluxing in the presence of Water for a prolongedperiod, c. g. 30 minutes. For example, treating the compound of Example1 in this manner produces 3-rnethylbenzothiazol-Z-one. Heating theintermediates of Formula I together with an alkali metal alcoholateproduces the 2-alkoxyl derivatives; for example, heating the compound ofExample 1 together with sodium methylate produces2-methoxybenzothiazole. Heating together the intermediates of Formula Iwith ammonia (ammonium hydroxide) produces the Z-amino derivatives; forexample, heating the compound of example 1 together with ammoniumhydroxide in a sealed tube produces 2-amino-3-methylbenzothiazole.

What we claim as our invention and desire secured by Letters Patent ofthe United States is:

l. A process for preparing cyanine dyes comprising condensing a compoundselected from the group consisting of those represented by the followingtwo general formulas:

and

wherein R2 represents an alkyl group, X1 represents an anion, nrepresents a positive integer of from 1 to 1, D1 represents thenon-metallic atoms necessary to complete a heterocyclic nucleus selectedfrom the group consisting of those of the benzothiazole series, those ofthe benzoselenazole series, and those of the naphthothiazole series, andZ2 and Q each represents the non-metallic atoms necessary to complete aheterocyclic nucleus containing from 5 to 6 atoms in the heterocyclicring.

2. A process according to claim 1 wherein said condensation is carriedout in the presence of a basic condensing agent.

3. A process for preparing 3,3-dimethyl-2,2-thiacyanine iodidecomprising condensing the methyl ester til of the methyl sulfate ofbenzothiazole-Z-sulfonic acid having the following formula:

C-S0a--CH3 CZHS 0802002115 together with1-carboxymethyl-3-phenyl-2-thiohydantoin in the presence of a basiccondensing agent.

5. A process for preparing 3-carboxymethyl-5-(3- ethyl 2(3)benzothiazolylidene)rhodanine comprising condensing the ethyl ester ofthe ethyl sulfate of benzothiazole-Z-sulfonic acid having the followingformula:

together with 3-carboxymethylrhodanine in the presence of a basiccondensing agent.

6. A process for preparing4-(3-ethyl-2(3)benzothiazolyl)-3-methyl-1-psulfophenyl-5-pyrazolonecomprising condensing the ethyl ester of the ethyl sulfate ofbenZothiazole-2-sulfonic acid having the following formula:

CSO3C2H5 together with 3-methyl-l-p-sulfophenyl-5pyrazolone in thepresence of a basic condensing agent.

7. A process for preparing 3,3'-dirnethyl-8-(2-ethyl-3"-methyl-2"-benzothiazolinyl)2,2-thiacyaninc iodide comprisingcondensing the methyl ester of the methyl sulfate ofbenzothiazole-Z-sulfonie acid having the following formula:

N CH3 osoio C11;

together with 2-(2'-ethyl-3 '-methyl-2 3 -benzothiazolyl)-methylbenzothiazole methiodide having the following formula:

in the presence of a basic condensing agent.

17 8. A process for preparing monomethine cyanine dyes comprisingcondensing in the presence of a basic condensing agent a compoundselected from those represented by the following general formula:

wherein R represents a primary alkyl group, X represents an acid anion,and Z represents the non-meta1lic atoms necessary to complete aheterocyclic nucleus of the benzothiazole series together with acompound selected from those represented by the following generalformula:

wherein R represents a primary alkyl group, X represents an acid anion,and Z represents the non-metallic atoms necessary to complete aheterocyclic nucleus of the benzothiazole series, together with acompound selected from those represented by the following generalformula:

/Q\ H26 b=O wherein Q represents the non-metallic atoms necessary tocomplete a heterocyclic nucleus containing from 5 to 6 atoms in theheterocyclic ring.

18 10. A trinuclear dye selected from those represented by the followinggeneral formula:

wherein R and R2 each represents an alkyl group, X represents an acidanion, D1 represents the non-metallic atoms necessary to complete aheterocyclic nucleus selected from the group consisting of those of thehenzothiazole series, those of the naphthothiazole series, and those ofthe benzoselenazole series, and Z represents the non-metallic atomsnecessary to complete a heterocyclic nucleus selected from the groupconsisting of those of the benzothiazole series and those of thenaphthothiazole series.

11. The trinuclear dye represented by the following formula:

s 0 ziz References Cited in the file of this patent UNITED STATESPATENTS 2,432,060 Anish Dec. 2, 1947 FOREIGN PATENTS 562,754 GreatBritain July 14, 1944

1. A PROCESS FOR PREPARING CYANINE DYES COMPRISING CONDENSING A COMPOUNDSELECTED FROM THE GROUP CONSISTING OF THOSE REPRESENTED BY THE FOLLOWINGTWO GENERAL FORMULA
 10. A TRINUCLEAR DYE SELECTED FROM THOSE REPRESENTEDBY THE FOLLOWING GENERAL FORMULA: